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eth/downloader: accumulating hash bans for reconnecting attackers

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This commit is contained in:
Péter Szilágyi
2015-05-29 21:04:20 +03:00
parent eedb25b22a
commit 84bc93d8cb
2 changed files with 126 additions and 5 deletions
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35
eth/downloader/downloader_test.go
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@ -14,6 +14,7 @@ import (
var (
knownHash = common.Hash{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
unknownHash = common.Hash{9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9}
bannedHash = common.Hash{5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5}
)
func createHashes(start, amount int) (hashes []common.Hash) {
@ -520,3 +521,37 @@ func TestMadeupParentBlockChainAttack(t *testing.T) {
t.Fatalf("failed to synchronise blocks: %v", err)
}
}
// Tests that if one/multiple malicious peers try to feed a banned blockchain to
// the downloader, it will not keep refetching the same chain indefinitely, but
// gradually block pieces of it, until it's head is also blocked.
func TestBannedChainStarvationAttack(t *testing.T) {
// Construct a valid chain, but ban one of the hashes in it
hashes := createHashes(0, 8*blockCacheLimit)
hashes[len(hashes)/2+23] = bannedHash // weird index to have non multiple of ban chunk size
blocks := createBlocksFromHashes(hashes)
// Create the tester and ban the selected hash
tester := newTester(t, hashes, blocks)
tester.downloader.banned.Add(bannedHash)
// Iteratively try to sync, and verify that the banned hash list grows until
// the head of the invalid chain is blocked too.
tester.newPeer("attack", big.NewInt(10000), hashes[0])
for banned := tester.downloader.banned.Size(); ; {
// Try to sync with the attacker, check hash chain failure
if _, err := tester.syncTake("attack", hashes[0]); err != ErrInvalidChain {
t.Fatalf("synchronisation error mismatch: have %v, want %v", err, ErrInvalidChain)
}
// Check that the ban list grew with at least 1 new item, or all banned
bans := tester.downloader.banned.Size()
if bans < banned+1 {
if tester.downloader.banned.Has(hashes[0]) {
break
}
t.Fatalf("ban count mismatch: have %v, want %v+", bans, banned+1)
}
banned = bans
}
}